title: SMAD2 and the relationship of colorectal cancer to inflammatory bowel disease.
abstract: Inflammatory bowel diseases (IBDs) affecting the colon [Crohn's disease (CD) and ulcerative colitis (UC)] are associated with an increased risk of colorectal cancer (CRC). Our previous work using oligonucleotide array data indicated that SMAD2 was significantly underexpressed in UC dysplastic tissue compared to benign UC. The aim of this current study was to determine whether single nucleotide polymorphisms (SNPs) within the SMAD2 gene are associated with IBD dysplasia/cancer. We performed an SNP haplotype-based case-control association study. Leukocyte DNA was obtained from 489 unrelated Caucasians (158 UC, 175 CD, 71 CRC, 85 controls). Eleven SNPs were genotyped. All 11 SNPs were in Hardy-Weinberg equilibrium in the control population. Strong linkage disequilibrium was observed among nearly all SMAD2 SNPs. There were no significant associations between SMAD2 allele or haplotype frequencies. Power calculations indicated good power for single-marker analysis (>0.8) and reasonably good power against effects of 0.1-0.15 for haplotype analysis. SMAD2 SNPs were not associated with the development of IBD dysplasia/cancer. This incongruity between our previous microarray data and the findings from this genotype study may be attributed to mechanisms such as alternative splicing of pre-mRNA SMAD2 and/or cross talk with other cellular pathways.
authors.affiliation: Price Institute of Surgical Research and the Section of Colorectal Surgery, Department of Surgery, University of Louisville School of Medicine, Louisville, Kentucky 40292, USA.
authors.forename: S S
authors.initials: SS
authors.lastname: Mahid
authors.forename: K S
authors.initials: KS
authors.lastname: Minor
authors.forename: B C
authors.initials: BC
authors.lastname: Brangers
authors.forename: G A
authors.initials: GA
authors.lastname: Cobbs
authors.forename: S
authors.initials: S
authors.lastname: Galandiuk
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D003093:Colitis, Ulcerative / Q000378:metabolism*; D015179:Colorectal Neoplasms / Q000378:metabolism*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006239:Haplotypes; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000378:metabolism*; D015810:Linkage Disequilibrium; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide; D051899:Smad2 Protein / Q000096:biosynthesis*
chemical_list: C497782:SMAD2 protein, human; D051899:Smad2 Protein